E-ALD: Tailoring the Optoeletronic Properties of Metal Chalcogenides on Ag Single Crystals

Technological development in nanoelectronics and solar energy devices demands nanostructured surfaces with controlled geometries and composition. Electrochemical atomic layer deposition (E-ALD) is recognized as a valid alternative to vacuum and chemical bath depositions in terms of growth control, quality and performance of semiconducting systems, such as single 2D semiconductors and multilayered materials. This chapter is specific to the E-ALD of metal chalcogenides on Ag single crystals and highlights the electrochemistry for the layer-by-layer deposition of thin films through surface limited reactions (SLRs). Also discussed herein is the theoretical framework of the under potential deposition (UPD), whose thermodynamic treatment open questions to the correct interpretation of the experimental data. Careful design of the E-ALD process allows fine control over both thickness and composition of the deposited layers, thus tailoring the optoelectronic properties of semiconductor compounds. Specifically, the possibility to tune the band gap by varying either the number of deposition cycles or the growth sequence of ternary compounds paves the way toward the formation of advanced photovoltaic materials

Electrical Behavior of Cd0.3Zn1.1x S0.7 Thin Films for Non-Heat Light Emitting Diodes

In developing countries like Kenya, solution processing technique is the cheapest and simplest technique to grow inorganic composites thin films. This method was used to grow thin films of Cd0.3Zn1.1xS0.7on ordinary microscope Perspex substrate slides from aqueous solutions of Zinc chloride and cadmium chloride in ammonia solution. A solution of triethanalomine was used as a complexing agent while thiourea was used as source of sulphide ions. Electrical properties as a function of their thicknesses were obtained by varying deposition time while all other parameters were maintained constant. Using a resistance measurement device and a Gauss meter, resistivity and the conductivity of the films were found to be thickness dependent with semiconductor nature

Thermochemistry of the E-ALD process for the growth of Cu x Zn y S on Ag(111): Interpretation of experimental data

The electrochemical atomic layer deposition (E-ALD) growth of chalcogenides materials enables the deposition of technologically interesting ultra-thin films. However, this method raises some questions about the actual growth mechanism. We addressed one of the more interesting anomalies reported lately: the occurrence of the Zn-deficiency and of the polycrystalline thread-like overgrown structures in the E-ALD growth of CuxZnyS. The present study was developed using a computational speciation approach under the mass balance method. Exploiting a well-established computational approach, but uncommonly applied to the electrochemical science, we calculated the predominance charts and the equilibrium speciation of the solid phases during the electrochemical process. On this basis, we obtained a deep insight into the mechanism underlying the E-ALD process from a thermodynamic standpoint. Thus, we identified the crucial steps of the CuxZnyS growth leading to the anomalies object of this research

Single Enzyme Synthesis and Bio-imitation of Functional Nanocrystals

Green synthesis methods of inorganic materials have gained lots of attention due to lower pollution and toxic precursors during the synthesis. One of the modern green methods of synthesis is biosynthesis in which a DNA, small peptide molecule, or amino acids plays the main role of synthesis. Biomineralization, the biosynthesis process happens in the nature by elements, has been considered as a green, low cost, and scalable method of synthesis. In comparison with conventional synthesis methods, biomineralization happens under ambient conditions in aqueous phase that can be applied for synthesis of inorganic nanostructure metal sulfide semiconductors gained interest due to their remarkable physical and chemical properties such as electronic, magnetic, and optical1. Their conventional synthesis methods of semiconductors are cost effective nowadays; however, Environmental-friendly biosynthesis is going to be a potential replacement in near future. Biomineralization of semiconductor nanocrystals (Quantum Dots) offers a low cost and greener approach of semiconductors under ambient conditions in aqueous phase in which a single enzyme plays the role of catalyzing the reaction and templating the nanostructure of quantum dots.To begin, we showed the templating role of a single protein in biosynthesis of CaCO3 crystallization. In nature, various crystal structure of CaCO3 formation happen by living organisms such as sea shells, snails, and corals. In this study, a single well-known protein, Silicatein α, has been utilized to be responsible for templating the crystal structure of CaCO3 mineralization at ambient conditions in aqueous phase. Templating vaterite and aragonite crystal structure, confirmed by XRD and SEM, in the presence of Silicatein showed a change in state level of CaCO3 crystal structure from calcite to vaterite and aragonite. Also, the influence of protein concentration on aragonite crystallization has been studied in this work that confirms the role of Silicatein in CaCO3 crystallization.Furthermore, we have focused on both roles of single enzyme in catalyzing and templating in biomineralization process. In this study, an engineered enzyme called cystathionine γ-lyase (CSE) has been playing two roles in biomineralization of various metal sulfides. First, CSE can turn over L-cysteine to generate reactive source of sulfur, H2S, in solution continuously. Second, CSE plays the role of templating the nanocrystal growth of metal sulfides.Single enzyme direct biomineralization of nontoxic metal chalcogenide such as ZnS by utilizing CSE enzyme was reported in this work. Synthesized ZnS, Zn1-xCdxS alloy, and ZnS-Zn1-xCdxS core-shell showed considerable optical properties such as great absorption and fluorescence lead to 97.6 ns increase in decay time confirmed by life time decay photoluminescent. Also, narrow size distribution, well crystallinity, nanomaterial composition and shape of QDs were characterized by HRTEM, HAADF, and EDAX. Biosynthesized method lead to achieve 7% enhancement in quantum yield.Also, we have synthesized SnS and Cu2ZnSnS4 alloy by utilizing CSE single enzyme in the presence of L-cysteine as a source of sulfur. Biosynthesized SnS nanocrystals and its relative compound, confirmed by XRD and HAADF, showed great photocatalytic property regard to the potential application in quantum dots-sensitized solar cell (QDSCs). SnS and CZTS have been applied as an absorber layer by in-situ growth on TiO2-paste as a working electrode in the presence of polysulfide electrolyte and Cu2S cathode. We have presented the uniform penetration of QDs into TiO2-paste by in-situ growth, confirmed by SEM-EDAX line scanning, that improved solar cell characterization parameters such as Voc, Jsc, and FF to 5.5 V, 3.1 mA/cm^2 , and 61%, respectively

Porous Single-Crystal-Based Inorganic Semiconductor Photocatalysts for Energy Production and Environmental Remediation: Preparation, Modification, and Applications

This is the peer reviewed version of the following article: Niu, J., Albero, J., Atienzar, P., García, H., Porous Single-Crystal-Based Inorganic Semiconductor Photocatalysts for Energy Production and Environmental Remediation: Preparation, Modification, and Applications. Adv. Funct. Mater. 2020, 30, 1908984, which has been published in final form at https://doi.org/10.1002/adfm.201908984. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] Semiconductor photocatalytic and photovoltaic performance depends on crystallinity and surface area to a large extent. One strategy that has recently emergyed to improve semiconductor photoresponse efficiency is their synthesis as porous single crystals (PSCs), therefore providing simultaneously high crystallinity, minimization of grain boundaries, and large specific surface area. Other factors, such as high density of active sites, and enhanced light absorption, also contribute to increased PSC photoresponse with respect to analogous bulk or amorphous materials. This review initially presents the concept and main properties of PSCs. Then, the synthetic routes and the applications as photocatalysts and as photovoltaic devices, mainly in sunlight applications, are summarized. The synthetic procedures have been classified according to the mechanism of pore generation. Applications cover photocatalysis for environmental remediation, solar fuels production, selective photooxidation of organic compounds, and photovoltaic devices. Finally, a summary and views on future developments are provided. The purpose of this review is to show how the use of PSCs is a powerful general methodology applicable beyond metal oxides and can ultimately lead to sufficient photoresponse efficiency, bringing these processes close to commercial application.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa SEV2016-0683 and RTI2018-89023-CO2-R1) and by the Generalitat Valenciana (Prometeo 2017-083) is gratefully acknowledged. J.N. also gratefully acknowledges financial support from the Fundamental Research Funds for the Central Universities (2019XKQYMS76).Niu, J.; Albero-Sancho, J.; Atienzar Corvillo, PE.; García Gómez, H. (2020). Porous Single-Crystal-Based Inorganic Semiconductor Photocatalysts for Energy Production and Environmental Remediation: Preparation, Modification, and Applications. Advanced Functional Materials. 30(15):1-51. https://doi.org/10.1002/adfm.2019089841513015Lee, B., Yamashita, T., Lu, D., Kondo, J. N., & Domen, K. (2002). 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Crystal-Growth Process of Single-Crystal-like Mesoporous ZnO through a Competitive Reaction in Solution. Crystal Growth & Design, 12(6), 2923-2931. doi:10.1021/cg300116hDong, J.-Y., Lin, C.-H., Hsu, Y.-J., Lu, S.-Y., & Wong, D. S.-H. (2012). Single-crystalline mesoporous ZnO nanosheets prepared with a green antisolvent method exhibiting excellent photocatalytic efficiencies. CrystEngComm, 14(14), 4732. doi:10.1039/c2ce06739kLuo, Q.-P., Wang, B., & Cao, Y. (2017). Single-crystalline porous ZnO nanosheet frameworks for efficient fully flexible dye-sensitized solar cells. Journal of Alloys and Compounds, 695, 3324-3330. doi:10.1016/j.jallcom.2016.10.130Xu, Y., Wen, W., & Wu, J.-M. (2018). Titania nanowires functionalized polyester fabrics with enhanced photocatalytic and antibacterial performances. Journal of Hazardous Materials, 343, 285-297. doi:10.1016/j.jhazmat.2017.09.044Dong, Q., Yin, S., Guo, C., Wu, X., Kumada, N., Takei, T., … Sato, T. (2014). 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Design Rules for Obtaining Narrow Luminescence from Semiconductors Made in Solution

Solution-processed semiconductors are in demand for presentandnext-generation optoelectronic technologies ranging from displaysto quantum light sources because of their scalability and ease ofintegration into devices with diverse form factors. One of the centralrequirements for semiconductors used in these applications is a narrowphotoluminescence (PL) line width. Narrow emission line widths areneeded to ensure both color and single-photon purity, raising thequestion of what design rules are needed to obtain narrow emissionfrom semiconductors made in solution. In this review, we first examinethe requirements for colloidal emitters for a variety of applicationsincluding light-emitting diodes, photodetectors, lasers, and quantuminformation science. Next, we will delve into the sources of spectralbroadening, including "homogeneous" broadening fromdynamical broadening mechanisms in single-particle spectra, heterogeneousbroadening from static structural differences in ensemble spectra,and spectral diffusion. Then, we compare the current state of theart in terms of emission line width for a variety of colloidal materialsincluding II-VI quantum dots (QDs) and nanoplatelets, III-VQDs, alloyed QDs, metal-halide perovskites including nanocrystalsand 2D structures, doped nanocrystals, and, finally, as a point ofcomparison, organic molecules. We end with some conclusions and connections,including an outline of promising paths forward

Crystal growth of functional materials by using CSVS and MOCVD:The AIIMnBVI and II-oxides case

En esta tesis se presenta un estudio en profundidad del crecimiento cristalino y la caracterización de algunos materiales funcionales de la familia II-VI. Las propiedades estructurales, morfológicas, ópticas y eléctricas estudiadas se han correlacionado con la metodología y condiciones de crecimiento cristalino utilizadas. Entre la variedad de materiales II-VI, se han elegido 2 familias de semiconductores debido a sus propiedades singulares. El primero incluye los óxidos del grupo II, con elementos como el Zinc y el Cadmio, con una alta transparencia en el rango óptico visible. Estos compuestos se pueden usar en diversas aplicaciones en optoelectrónica, incluyendo su uso como óxidos conductores transparentes (TCO). El otro conjunto de materiales estudiados son algunos semiconductores magnéticos diluidos (DMS) basados en los compuestos ZnS y ZnTe con Manganeso que además de las propiedades semiconductoras habituales, tienen propiedades magnéticas interesantes. Con el fin de crecer los compuestos binarios y ternarios estudiados en esta tesis, se han utilizado dos métodos de crecimiento: un sistema de deposición CVD basado en la descomposición de compuestos metal-orgánicos (MOCVD), técnica con control multiparamétrico y un método más simple como es la sublimación en vacío a corta distancia (CSVS). De acuerdo con los objetivos de la tesis, la caracterización de las muestras se ha realizado utilizando las siguientes técnicas: microscopía de fuerza atómica (AFM), microscopía electrónica de barrido (SEM) y microscopía electrónica de transmisión (TEM), análisis de difracción de rayos-X (XRD), espectroscopía dispersiva de rayos-X (EDX), mediciones de emisión de rayos-X inducida por partículas (PIXE) y medidas de reflectividad y transmision óptica. Así pues, se crecieron capas delgadas de ZnO mediante el método MOCVD sobre diferentes planos de corte del zafiro. La banda prohibida directa del ZnO (~ 3.4 eV) proporciona un buen grado de transparencia óptica en la region visible del espectro electromagnético, y sus propiedades piezoeléctricas son ideales para la aplicación en filtros de ondas acústicas de superficie (SAW). El uso de este material en campos como la fotónica y la microelectrónica hace que la obtención de capas de espesor nanométrico, manteniendo una buena calidad morfológica y estructural, sea un desafío fundamental. En esta tesis se ha realizado un estudio sistemático de la disminución del espesor y rugosidad de las capas de ZnO en función de las condiciones de crecimiento (flujo del precursor, temperatura de crecimiento y tiempo de crecimiento). De manera complementaria se ha realizado un tratamiento químico del sustrato con el objetivo de aumentar los puntos de nucleación. Este estudio sistemático ha resultado en el logro y caracterización de capas de alta calidad con espesores de aproximadamente 34 nm y una rugosidad del orden de 2 nm. Teniendo en cuenta la posibilidad de cambiar las propiedades de los compuestos binarios (como la densidad de portadores o la energía del bandgap) mediante la aleación del material con otro elemento, se llevó a cabo el crecimiento de la aleación CdZnO. Una de las principales dificultades para obtener este compuesto ternario con propiedades deseables y buena calidad cristalina es la debida a la diferencia entre las estructuras cristalinas del ZnO (wurtzita) y el CdO (cúbico). La mayor parte del trabajo que se puede encontrar en la literatura está dedicado a compuestos ternarios con un alto contenido de zinc o cadmio, mientras que el estudio de la transición entre las fases cúbica y wurtzita ha recibido menos atención. En esta tesis hemos profundizado en el crecimiento de la región rica en cadmio de la aleación sobre R-zafiro, mostrando el límite de solubilidad del Zn, en las condiciones experimentales analizadas, y cómo la transición de la fase cúbica a una en la que coexisten ambas fases afecta a las propiedades estructurales de este compuesto ternario. Además, se ha analizado la influencia del gas portador sobre las características estructurales y ópticas de las capas delgadas obtenidas. En el mismo marco de estudio de la familia II-VI, el CdTe ocupa un lugar de privilegio. Este material se utiliza a menudo como capa absorbente en heteroestructuras de CdTe/CdS. Por otro lado, las heteroestructuras con TCO, en particular la heterounión p-n CdTe/CdO, han sido menos estudiadas. La complejidad en la obtención de esta heteroestructura se debe, entre otros factores, al desajuste de red entre el CdO y el CdTe. Los parámetros de crecimiento se eligieron de tal manera que las tensiones entre las capas de la heteroestructura de CdTe/CdO/R-zafiro crecida por el método MOCVD se minimizaran. El estudio de la diferencia de potencial de contacto (CPD) y el cambio en el fotovoltaje superficial (SPV) en función de la potencia aplicada del láser incidente, se han analizado en correlación a la temperatura de crecimiento. Por otro lado, los DMS combinan elementos de la física de los semiconductores y el magnetismo, lo que constituye una oportunidad única para la investigación y la tecnología. A diferencia de las aleaciones de semiconductores clásicas, la distribución aleatoria de iones magnéticos conduce a la aparición y desarrollo de fases magnéticas individuales. La inclusión de átomos de Mn en la red II-VI es particularmente interesante ya que conduce a fenómenos como la magnetorresistencia negativa, la rotación de Faraday gigante y el comportamiento del vidrio de spin. Así, hemos estudiado el crecimiento y caracterización de la aleación de ZnS y ZnTe con Mn, debido a la banda prohibida ancha que presentan y a las características ópticas derivadas que pueden presentar estas aleaciones, que las hace atractivas para aplicaciones fotovoltaicas. Así, hemos obtenido capas delgadas de ZnMnTe y ZnMnS sobre vidrio mediante la técnica CSVS. Nuestro estudio mostró el límite de solubilidad del Mn en nuestras condiciones experimentales, y cómo la incorporación de manganeso afecta las características estructurales, subestructurales y ópticas de los correspondientes compuestos ternarios.This thesis presents an in-depth study of the crystal growth and characterization of some functional materials of the II-VI family. The studied structural, morphological, optical and electrical properties have been correlated with the crystal growth methodology and growth conditions used. Among the variety of II-VI materials, 2 groups of semiconductors have been chosen due to their unique properties. The first includes oxides of II-group, with elements such as Zinc and Cadmium, with high transparency in the visible optical range. These compounds can have applications in optoelectronics and can be used as transparent conductive oxides (TCOs). The other group of studied materials is some diluted magnetic semiconductors (DMS) based on Manganese and the II-VI semiconductors ZnS and ZnTe. In addition to the usual semiconductor properties, the Mn alloyed materials can have interesting magnetic properties. In order to grow the binary and ternary compounds studied in this thesis, two growth methods have been used, the more accurate, multiparameter-controlled Metal-Organic Chemical Vapor Deposition (MOCVD) method and the simpler Close Space Vacuum Sublimation (CSVS). The characterization of the samples has been done using the following techniques: atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), energy-dispersive X-ray spectroscopy (EDX), particle-induced X-ray emission (PIXE) and optical reflectance and transmission measurements. Thus, ZnO thin films were grown using the MOCVD method on the crystal planes C-, A-, M- and R- of sapphire substrates. The ZnO direct bandgap of ~ 3.4 eV provides a good degree of optical transparency in the visible region of the electromagnetic spectrum, and its piezoelectric properties are ideal for application on surface acoustic waves (SAWs) filters. Moreover, ZnO has shown its potentiality in fields such as photonics and microelectronics. In this regard, obtaining layers of nanometric thickness, while maintaining a good morphological and structural quality, is both a requirement and a challenge. In this thesis, a systematic study of the thickness and roughness decrease of the ZnO layers has been undertaken as a function of the growth conditions (precursor flux, growth temperature and time). In a complementary manner, a chemical treatment of the substrate has been carried out, in order to increase the nucleation points. This systematical study has resulted in the attainment and characterization of high-quality layers with thicknesses of about 34 nm and roughness of about 2 nm. Taking into account the possibility of changing the properties of binary compounds (such as the carrier density or bandgap energy) by alloying the material with another element, the growth of the CdZnO alloy was carried out. One of the main difficulties in obtaining this ternary compound with desirable properties and good crystal quality is due to the difference in crystal structures between ZnO (wurtzite) and CdO (cubic). Most of the works that can be found in the literature are devoted to the ternary with high content of zinc or cadmium, while the study of the transition between the cubic and wurtzite phases has received less attention. In this thesis, we have delved into the growth of the cadmium rich region of the alloy on R-sapphire, and we have found the solubility limit of Zn under our experimental conditions, and how the transition from the cubic phase to a mixed one affects the structural properties of this ternary compound. Additionally, the influence of the carrier gas on some structural and optical features of the CdZnO thin layers has been analyzed. In the same frame of studying the II-VI family, CdTe stands out as one of the most significant of this family. CdTe is often used as an absorber layer in CdTe/CdS heterostructures. Nevertheless, heterostructures with TCO, in particular the p-n-heterojunction CdTe/CdO, have been less studied. The complexity in obtaining this structure is due to, among other factors, the lattice mismatch between CdO and CdTe. In this thesis, the growth parameters were chosen in such a way that the stresses between the layers of the CdTe/CdO/R-sapphire heterostructure grown by the MOCVD method are minimized. The study of the Contact potential difference (CPD) and the change in the Surface photo voltage (SPV) as a function of the applied power of the incident laser have been analyzed in correlation with the growth temperature. On the other hand, DMS, as said before, combine elements of the physics of semiconductors and magnetism, which is a unique opportunity for research and technology. Unlike in classical semiconductor alloys, the random distribution of magnetic ions leads to the appearance and development of individual magnetic phases. Among alloying elements, the inclusion of Mn atoms in the II–VI lattice is particularly interesting since it leads to phenomena such as negative magnetoresistance, giant Faraday rotation and spin glass behavior. We have studied the growth and characterization of the ZnS and ZnTe alloying with Mn, due to the wide bandgap and optical features that these alloys can present, which make them attractive for photovoltaic applications. Thus, ZnMnTe and ZnMnS thin films were obtained on glass substrates by the CSVS technique. The study has shown the Mn solubility limit under our experimental conditions, and how the incorporation of manganese affects the structural, substructural, and optical characteristics of the ternary compounds

Control Over Cadmium Chalcogenide Nanocrystal Heterostructures via Precursor Conversion Kinetics

Semiconductor nanocrystals have immense potential to make an impact in consumer products due to their narrow, tunable emission linewidths. One factor limiting their use is the ease and reproducibility of core/shell nanocrystal syntheses. This thesis aims to address this issue by providing chemical control over the formation of core/shell nanostructures by replacing engineering controls with kinetic controls. Chapter 1 contextualizes our study on nanoparticle synthesis with a brief discussion on the physics of quantum confinement and the importance of narrow size dispersities, core/shell band alignments, and low lattice mismatches and strain at core/shell nanocrystal interfaces. Next, the evolution of cadmium chalcogenide nanocrystal reagents is described, ranging from the original organometallic reagents used in the 1980s to modern approaches involving cadmium phosphonates and carboxylates. This is followed by a description of chalcogen precursors, highlighting the recent introduction of molecules whose well-controlled and tunable reaction rates allow for the size tuning of nanocrystals at 100% yield, and accompanying theories on nanocrystal nucleation. Chapter 2 covers work to expand the library of available sulfur precursors to a wider range of molecules relevant for the synthesis of cadmium sulfide nanocrystals. Using thioureas alone, only very fast or very slow precursor conversion rates can be accessed. This limits the accessible sizes of cadmium sulfide nanocrystals using a single hot injection of precursor at standardized reaction conditions. We observe that thiocarbonate and thiocarbamate precursors with varying electronic substituents allow access to intermediate precursor conversion rates and cadmium sulfide nanocrystal sizes. Interestingly, we note that these new precursor classes nucleate particles with higher monodispersity than ones synthesized from thioureas. These results indicate that in addition to precursor structure controlling precursor conversion rate, precursor structure additionally impacts nanocrystal monodispersity. Chapter 3 expands the library of sulfur and selenium precursors to include cyclic thiones and selenones which extends chemical control of precursor conversion kinetics to cover five orders of magnitude. This unprecedented breadth of rate control allows for the simultaneous hot injection of multiple precursors to generate core/shell or alloyed nanoparticles using precursor reactivity. Using this new synthetic strategy, we observe that kinetic control runs into several issues which we partially attribute to differences in cadmium sulfide and cadmium selenide critical concentrations and growth rates. Nevertheless, combined with a syringe pump shelling method, we are able to access core/shell and alloyed nanocrystals with photoluminescence quantum yields of 67-81%. Chapter 4 applies the concept of nanostructure control via precursor conversion kinetics to a better model system: two-dimensional nanoplatelets. Cadmium chalcogenide nanoplatelets are highly desirable materials due to their exceptionally narrow emission full width half max (FWHM) values which make them pure emitters relative to quantum dots or organic dyes. We synthesize 3 monolayer thick nanoplatelets whose lateral dimensions vary from 10 nm x 10 nm to 186 x 100 nm and demonstrate compositional control on the smallest platelet sizes with STEM EELS

DEVELOPMENT AND CHARACTERIZATION OF NANOSTRUCTURED MATERIALS FOR ORGANIC AND HYBRID SOLAR CELLS

In the last years, the massive evolution of modern technologies has gradually created an alarming gap between the production and the consumption of energy. Traditional energy resources are no longer sufficient to satisfy the demand of energy without spoiling earth environment. Solar photovoltaics represents a highly promising technology to tackle this global energy issue. The thorough scientific discussion on this fundamental topic gave rise to interesting results and the organic solar cells (OSCs) are one of these achievements. One major reason of the development and the increasing interest in this new technology is its eco-friendliness and the potentially low-cost production of solar modules on flexible (plastic) substrates. Furthermore, new applications are expected by flexible or semitransparent organic solar cells. Nevertheless, two main problems must be overcome before this promising technology replaces the long-established silicon solar cells: the low power conversion efficiency and the scarce stability. In order to tackle these fundamental issues the research efforts must be focused towards both the development of new materials and their detailed photophysical and morphological characterization. Recently the application of nanostructured architectures within the active layers of OSCs has demonstrated to be an efficient alternative to boost solar cell efficiency. Indeed, the nanometric miniaturization of materials opened a huge amount of possibilities to tune and bolster their optical and electrical properties. In this thesis work, the potentialities of the nanostructured architectures are explored. In particular, the attention of this work is addressed towards the development and the photophysical characterization of new hybrid nanostructured photoactive materials. Three different families of nanostructures, colloidal Quantum Dots, Carbon Dots, and hybrid organic/inorganic perovskite nanoparticles, are blended with organic photovoltaic materials. The thorough investigation of the photo-physical and morphological interactions between the nanostructures and the organic materials aims to investigate these nanocomposite as new photoactive materials for next-generation solar cells. The first step of the work focuses on the investigation of a prototypical active layer consisting in binary blends of the fullerene derivative PCBM and CdSe/CdS core-shell Quantum Dots (QDs) capped with different ligands (namely, oleylamine, octadecanethiol, and propanethiol). The double purpose is both to demonstrate that QDs do not influence only the morphology of the active layers, as it is often reported in literature, but also its photophysics and to unravel the pivotal role of QDs ligands on the electron transfer process, which is fundamental for organic solar cells. Through the combined use of steady-state, time resolved and pulsed electron paramagnetic resonance (EPR) techniques the photophysical role of QDs in OSCs is clarified and the possibility to tailor the electron transfer process through the proper choice of QDs ligands is demonstrated. The second part of the work aims at promoting the application of carbon dots (CDs) as electron donor materials for OSCs. CDs seem to be a good alternative to colloidal QDs, thanks to their low toxicity, good biocompatibility and peculiar photo-physical properties, however their poor solubility in organic solvents and mediocre electron-donor properties hampered their photovoltaic application. To tackle these critical issues, the synthesis and photo-physical characterization of N-doped CDs functionalized with two different thiophene-containing groups is carried out in this work. The functionalization intends to enhance the electron donating properties of the CDs and improve their solubility in organic solvents. The increased solubility allows to investigate the photoinduced interactions of functionalized CDs with the PCBM in solution and in solid blends. Through the combined cyclic voltammetry, optical and EPR analysis the enhanced electron donor capabilities of the functionalized CDs are demonstrated and the electron transfer process is characterized in detail. Finally, the last part of the work concentrates on the hybrid organic inorganic perovskite nanostructures. These recent nanostructures are definitely the best candidate to compete with silicon solar cells since their bulk counterpart has already provided record photovoltaic efficiencies in less than five years. However, the application of perovskite nanoparticles (PNPs) in organic solar cells has been scarcely investigated so far. Therefore, in this thesis work the synthesis of PNPs and the investigation of their interaction with both the PCBM and the semiconducting polymer P3HT is carried out. After the confirmation of the obtained synthesis through optical spectroscopy, X-ray diffraction and XPS analysis, the electron transfer from PNPs to PCBM is investigated. In particular, the effect of the ligand length on the electron transfer is examined, probing the process with two different PNPs ligands: octylamine and oleylamine. Successively, the role of the PNPs in blend with P3HT is studied. A triple effect of PNPs on the polymer properties is observed: (1) an increment of the dimension of P3HT crystalline domains, (2) a p-doping of the P3HT, and (3) an enhanced interchain order. The results of this work underpin the relevance of applying nanostructured architectures in organic photovoltaic materials, highlighting their beneficial role not only in morphology, but also in the main photo-physical processes that take place in solar cells. Additionally, the relevant role of the tailored surface engineering of nanostructures in the process of solar energy conversion is evidenced. All these observations aim at providing guidelines for the design and the fabrication of highly efficient solar cells